U.S. Pat. No. 6,460,866 to Altschul et al. teaches a combined wheeled vehicle and article carrier in which a pair of front wheels are mounted on a base below the carrier. A foot board is pivotally mounted at its front end to the base. The rear end of the foot board has a rear wheel so that the foot board may support a rider when the board is locked in horizontal position. The board may be rotated vertically to a retracted position with the rear wheel up. The device may then be trundled about by an uppermost handle while being supported only by the front wheels. But it does not stand securely on the two wheels.
U.S. Pat. No. 6,688,614 to Hsu teaches a combined wheeled vehicle and article carrier in which a pair of front wheels are mounted on a base below the carrier. A foot board is pivotally supported at its front end to the base. The rear end of the foot board has a rear wheel so that the foot board may support a rider when the board is in horizontal position. There are no provisions for fixing the foot board at right angles to the vertical in the horizontal position. This makes use as a scooter uncomfortable. The foot board may be lifted off the base. The board may be moved to a stable retracted vertical position. When being pulled by the handle in the retracted position, the assembly is not supported by a pair of rear wheels in what is the preferred function.